1. Field of the Invention
This invention relates to a wavelength-variable light source apparatus containing a light power meter and having a wavelength measurement function for measuring the wavelength characteristic of an object to be measured.
2. Description of the Related Art
Hitherto, normally a semiconductor laser of an external resonator type (the semiconductor laser will be hereinafter referred to as LD) has been used as a wavelength-variable light source and an optical filter which is a wavelength selection element has been inserted into an external resonator for providing single-mode oscillation. The wavelength passing through (or reflected on) the optical filter is made mechanically variable, thereby enabling wavelength sweeping in a wide range.
A light wavelength analysis system is realized which uses such a wavelength-variable light source and a light spectrum analyzer in combination for measuring the wavelength characteristic of an object to be measured and displaying and analyzing the wavelength characteristic.
Another light wavelength analysis system is also realized wherein a wavelength-variable light source and a light power meter are connected to a personal computer and are controlled from the personal computer for measuring the wavelength characteristic of an object to be measured and displaying and analyzing the wavelength characteristic on the personal computer.
However, the conventional light wavelength analysis system comprising a wavelength-variable light source and a light spectrum analyzer in combination involves the following problem:
With the light spectrum analyzer, if an attempt is made to analyze the wavelength of light emitted from the wavelength-variable light source at high resolution, it is necessary to take a long focal length of swept light as a restriction of the structure of the light spectrum analyzer. Inevitably, the cabinet of the light spectrum analyzer is upsized as compared with the size of the wavelength-variable light source and improvement in the wavelength resolution is limited. Therefore, it is impossible to build the light spectrum analyzer in a wavelength-variable light source apparatus and reduce the costs of the light wavelength analysis system; since the structure of the light spectrum analyzer itself is complicated, it is furthermore difficult to reduce costs of the light wavelength analysis system.
Further, to measure the wavelength characteristic, the wavelength to be detected needs to be calibrated between the wavelength-variable light source and the light spectrum analyzer, thus intricate operation to measurement becomes necessary and ease of operation needs also be considered.
With the conventional light wavelength analysis system comprising a wavelength-variable light source and a light power meter connected to a personal computer, the personal computer becomes necessary in addition to the wavelength-variable light source and the light power meter, thus it is difficult to reduce the costs of the light wavelength analysis system.
Further, since the wavelength-variable light source and the light power meter are controlled from the personal computer for measuring the wavelength characteristic of an object to be measured, a restriction that the measurement speed is determined by the control signal transmission speed from the personal computer to the wavelength-variable light source and the light power meter occurs and speeding up the wavelength measurement is hindered.
It is therefore an object of the invention to provide a wavelength-variable light source apparatus which contains a light power meter, can speed up wavelength measurement and simplify measurement operation while maintaining high wavelength resolution, and has a display function and an analysis function of the wavelength characteristic of an object to be measured for providing a light wavelength analysis system at low costs.
In order to achieve the above object, according to a first aspect of the invention, there is provided a wavelength-variable light source apparatus comprising: a wavelength-variable light source section having an external resonance part for externally resonating emitted light from a semiconductor laser light source at a predetermined wavelength and for varying an external resonance condition in the external resonance part; a control section for controlling the wavelength in the wavelength-variable light source section; and a light detection section for allowing light of each wavelength emitted from the wavelength-variable light source section to be incident on an object to be measured and detecting a light output level of output light of each wavelength emitted from the object to be measured, wherein the control section analyzes a light wavelength characteristic of the object to be measured based on the light output level of each wavelength detected by the light detection section.
Therefore, wavelength measurement can be speeded up and measurement operation can be simplified while high wavelength resolution is maintained, and the wavelength-variable light source apparatus forming a light wavelength analysis system at low costs can be provided without using a large-sized and expensive spectrum analyzer, a personal computer for external control, or the like as in the conventional system.
Further, according to a second aspect of the invention, there is provided a wavelength-variable light source apparatus comprising: a wavelength-variable light source section having an external resonance part for externally resonating emitted light from a semiconductor laser light source at a predetermined wavelength and for varying an external resonance condition in the external resonance part; a control section for controlling the wavelength in the wavelength-variable light source section; and a light detection section for allowing light of each wavelength emitted from the wavelength-variable light source section to be incident on an object to be measured, detecting a light output level of output light of each wavelength emitted from the object to be measured, and sending a signal indicating the light output level to the control section over an exclusive communication line, wherein the control section has a communication function for connecting to the light detection section over the exclusive communication line and analyzes a light wavelength characteristic of the object to be measured based on the light output level of each wavelength sent by the light detection section.
Therefore, wavelength measurement can be speeded up and measurement operation can be simplified while high wavelength resolution is maintained, and the wavelength-variable light source apparatus forming a light wavelength analysis system at low costs can be provided without using a large-sized and expensive spectrum analyzer, a personal computer for external control, or the like as in the conventional system. Further, transfer of the control signals and the light output level signal between the control section and the light detection section can be speeded up owing to the exclusive communication line; the measurement speed can be more increased.